Wireless frequency spectrum is controlled by government bodies. These government bodies allocate the frequency spectrum to particular wireless operators, and place conditions on how the frequency spectrum is used. For example, allocated frequency spectrum is typically required to operate either in a time division duplex (TDD) or frequency division duplex (FDD) mode. In a system that operates in a TDD mode, the uplink and downlink channels share the same frequency band, but are transmitted and received by the base station during mutually exclusive periods of time, as illustrated in FIG. 1. In a system that operates in an FDD mode, the uplink and downlink channels are transmitted simultaneously on different frequency bands, as illustrated in FIG. 2.
The 2.5 GHz frequency spectrum currently consists of TDD spectrum, and is being partially re-banded to support FDD. Currently, code division multiple access (CDMA) and the IEEE 802.16 standard, which uses orthogonal frequency division multiple access (OFDMA), both support TDD and FDD modes. Typically, systems which use CDMA or the IEEE 802.16 standard operate in either a TDD or FDD mode. Accordingly, it would be desirable to provide systems and methods that operate using both TDD and FDD channels.